动态创建对象

单元一代码：

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls, ComCtrls;

type
  TControlClass =class of TControl;
  TForm1 = class(TForm)
    RadioGroup1: TRadioGroup;
    Button1: TButton;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
  private
  public
  end;

var
  Form1: TForm1;

implementation

uses Unit2;


{$R *.dfm}


procedure TForm1.Button1Click(Sender: TObject);
const
 ContrlClassArry:array[0..2] of TControlClass=(TMonthCalendar,TMemo,TColorBox);
var
  i:integer;
  ControlObj:TObject;
begin
  //清理对象
  for  i:=0  to controlcount-1 do
  if (Controls[i] is TMonthCalendar) or (Controls[i] is TMemo)
     or (Controls[i] is TColorBox) then
  Controls[i].Free;
  //创建对象
  ControlObj:=TControlFactory.createControlObj(self,ContrlClassArry[RadioGroup1.ItemIndex]);
  label1.Caption:=ControlObj.ClassName;
  //测试对象
  if (ControlObj is  TMemo) then  TMemo(ControlObj).Lines.Add('测试成功！') ;
  if (ControlObj is  TColorBox) then  TColorBox(ControlObj).ItemIndex:=2 ;
end;


end.

 

单元二代码：

unit Unit2;

interface
uses
  Windows, SysUtils, Classes,Controls, Forms;

Type
  TControlClass =class of TControl;
  TControlFactory=class
  public
    class function createControlObj(AOwner:TWinControl ;ControlClass:TControlClass):TControl;
  end;

implementation

class function TControlFactory.createControlObj(AOwner:TWinControl ;ControlClass:TControlClass):TControl;
var
  FControlObj:TControl;
begin
  FControlObj:=ControlClass.Create(AOwner);
  FControlObj.Parent:=AOwner;
  FControlObj.Name:=FControlObj.ClassName;
  FControlObj.SetBounds(10,10,250,150);
  result:=FControlObj;
end;

end.